1. Field of the Invention
The present invention is directed generally to a contact arrangement for a relay including an improved contact spring. In particular, a contact spring in a relay has a spring leg having one end secured and a free end with a contact piece pressing against a cooperating contact element in the closed position of the contact and is lifted off from the cooperating contact element in the open condition of the contact by an actuation element.
2. Description of the Related Art
There are a great number of relays having contact arrangements similar to that described above. For example, a German utility model No. 82 35 283 discloses such a relay in which the contact spring is pre-stressed by means of a pre-stress bend extending transversely relative to a longitudinal direction of the spring leg. Relays of this type have a simple structure where the contact spring is frequently directly joined to the armature or actuation element. Such relays are often utilized for switching high DC loads; for example, one application provides a relay of this type for switching lamp circuits in motor vehicles where peak currents can reach 180 amperes. Such high switching loads lead to the formation of arcs which can frequently cause welding of the contacts and, thus, failure of the relay. This is particularly true when the relays undergo turn-on chattering. To prevent such premature breakdown of the relay, however, it is necessary to achieve high break-open forces so that contacts which are slightly welded together can be opened again and the relay remains functional. It is known to provide high-power springs as the contact spring for resetting the contact for this purpose. This, of course, requires a corresponding increase in the attractive force and in the response excitation power for the relay. It is also advantageous to provide a great over-lift or over-travel of the armature when the armature is closing the contact. Due to such increased excitation power, however, the pre-stress or the increased restoring force cannot be selected arbitrarily high.